WHO denies that countries hoard H5N1 samples

May 13, 2005 (CIDRAP News) – The World Health Organization (WHO) today denied a widely publicized report that countries dealing with H5N1 avian influenza have been refusing to share clinical samples from human patients, making it difficult for the WHO to monitor changes in the virus.

The British journal Nature this week published a news article saying that affected countries are "failing, or refusing" to share human samples with the WHO. It said the agency had obtained only six samples from the dozens of people who contracted the virus this year.

But the WHO's Western Pacific Regional Office denied that report in a statement today. "There is no refusal to share human samples by Viet Nam or any other country with avian influenza cases," the statement said. It said Vietnam has provided more than 100 clinical samples this year.

"What influenza experts have expressed concern about is the limited number of viruses derived from these samples," the agency said. "The yield of viruses has been very low for reasons yet to be elucidated."

At least 89 people have been infected with the H5N1 virus since early 2004, and at least 52 have died. The WHO has warned repeatedly that the virus may trigger a human flu pandemic if it gains the ability to spread easily from person to person. Several family clusters and some asymptomatic or mild cases in Vietnam in recent months have signaled that the virus may be evolving into a form that is less virulent but spreads more easily. But very little information from genetic studies of the virus has been available.

The Nature article also said that the WHO's sister agency, the United Nations Food and Agriculture Organization (FAO), has received few H5N1 samples collected from poultry. The article quoted Michael Perdue, head of animal influenza liaison at the WHO, as complaining that the FAO has not been sharing with the WHO the samples it does have.

But today's WHO statement said criticism of the FAO "is not appropriate as FAO does not receive any animal virus samples; instead, FAO, in collaboration with the World Organisation for Animal health (OIE), relies on the joint FAO/OIE network of national and international reference laboratories for the handling of such samples."

The WHO statement concludes, "We regret the misimpressions caused by this [Nature] story, some of which WHO staff contributed to."

Aside from the question of sample sharing, it's clear that experts are finding it hard to determine whether the virus has mutated or whether mutations are affecting its impact on humans.

The Nature article quoted Perdue as saying that several of the six human samples the WHO received from Vietnam contained mutated forms of the H5N1 virus, but that is not enough evidence to demonstrate a broad change in the pathogen.

To link a mutation with changes in the virus's behavior in humans would require analysis of hundreds of samples and full clinical data on the cases from which they came, Klaus Stohr, head of the WHO's global influenza program, is quoted as saying in the Nature article. Stohr said such large-scale studies "aren't happening."

Peter Cordingley, a spokesman for the WHO Western Pacific Office, said much the same thing in an Agence France-Presse report published today. When he was asked if the virus has changed, he said, "We can't do enough tests. We need a real heavy set of data before drawing conclusions."